binding-blocked-by-unscopables.js (1400B)
1 // Copyright 2015 Mike Pennisi. All rights reserved. 2 // This code is governed by the BSD license found in the LICENSE file. 3 4 /*--- 5 es6id: 8.1.1.2.1 6 description: > 7 True-coercing `Symbol.unscopables` properties block access to object environment record 8 info: | 9 [...] 10 6. If the withEnvironment flag of envRec is false, return true. 11 7. Let unscopables be Get(bindings, @@unscopables). 12 8. ReturnIfAbrupt(unscopables). 13 9. If Type(unscopables) is Object, then 14 a. Let blocked be ToBoolean(Get(unscopables, N)). 15 b. ReturnIfAbrupt(blocked). 16 c. If blocked is true, return false. 17 18 ES6: 13.11.7 (The `with` Statement) Runtime Semantics: Evaluation 19 [...] 20 6. Set the withEnvironment flag of newEnv’s EnvironmentRecord to true. 21 [...] 22 flags: [noStrict] 23 features: [Symbol.unscopables] 24 ---*/ 25 26 var x = 0; 27 var env = { x: 1 }; 28 env[Symbol.unscopables] = { x: true }; 29 30 with (env) { 31 assert.sameValue(x, 0, 'literal `true` value'); 32 } 33 34 env[Symbol.unscopables].x = 'string'; 35 with (env) { 36 assert.sameValue(x, 0, 'non-empty string values'); 37 } 38 39 env[Symbol.unscopables].x = 86; 40 with (env) { 41 assert.sameValue(x, 0, 'non-zero number values'); 42 } 43 44 env[Symbol.unscopables].x = {}; 45 with (env) { 46 assert.sameValue(x, 0, 'object values'); 47 } 48 49 env[Symbol.unscopables].x = Symbol.unscopables; 50 with (env) { 51 assert.sameValue(x, 0, 'Symbol values'); 52 } 53 54 reportCompare(0, 0);